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  • Map of MDAC extent created from a side scan survey of Holden Reef boundary region 2017. This Annex I habitat 'Submarine structures made by leaking gases' is within the Pen Llyn a'r Sarnau/Lleyn Peninsula and the Sarnau SAC.

  • Reporting under Article 17 of the EU Habitats Directive requires member states to report on progress towards achieving favourable conservation status for habitats and species of Community Importance. The assessment of conservation status does not only relate to that component of the habitat area or species population to be found in Special Areas of Conservation, but to the totality of the habitats and species throughout the United Kingdom. The results of NRW's feature monitoring work and other evidence collected (survey) or collated (other data sources) on reef feature extent feed in to the process of mapping and reporting under Article 17. JNCC coordinate and provide UK-level feature reports under Article 17; England, Wales, Northern Ireland and Scotland submit country-level data and information to inform these reports. This dataset only consists of the Welsh component of the Article 17 reef mapping.

  • Biogenic horse mussel (Modiolus Modiolus) reef is an important feature of the Pen Llyn a'r Sarnau SAC. The reef has high biodiversity and is vulnerable to anthropogenic activities, such as benthic fishing. The mussel reef forms an undulating surface that is significantly different to the surrounding seabed and therefore acoustic monitoring methods can be used to monitor changes in extent and identity areas of potential damage. Work is carried out on the north Llyn horse mussel reef in Pen Llyn a'r Sarnau jointly by CCW and University of Wales Bangor. Project is carried out in conjunction with the Across Wales drop-down video project.

  • As part of the HABMAP project surveys were carried out in 5 areas in the summer of 2005. Survey work carried out in Caernarfon Bay showed this area was very diverse in terms of both its seabed features and benthic communities. The location of a well-documented horse mussel (Modiolus modiolus) reef was clearly identified from multibeam bathymetry and backscatter data, and was sampled using video, SPI and grab samples. The area was rich in both infauna and epifauna, with a variety of different biotopes being recorded. Other features of the Caernarfon Bay survey area included an area of cobble and boulder ridges in the southwest with associated tide-swept epifaunal communities, and an area of muddy sediments in shallower waters to the east, with patches of stable cobbles that upported a rich seaweed and epifaunal community.

  • The section of the Menai Straits that were surveyed were divided into three parts. The hardness/roughness isopleths were combined using CAMRIS GIS to produce a composite map showing 7 types of group (very hard/very rough; hard/rough; moderately hard/moderately rough; moderately soft/moderately smooth; soft/moderately rough; soft/smooth; very soft/very smooth). A map for the whole of the survey area was followed by a map showing the biotope types as observed using the remote video, which are as follows (SA = superabundant; A = abundant; C = common; O = occasional) Sand/shell: Medium fine sand with shell: very silty. Coarse sand/silt: Coarse sand: very silty. Gravel: Barren Silty cobble: Silt accretion (A); Cerianthus (O-C); Urticina (O-C). Silty cobble/rich: Silt accretion (A); sponges (Haliclona, Halichondria) (C); hydroids (C); Urticina (O-C). Boulder/cobble sponge: Similar to above, but with sponges C-A. Cobble/bounder faunal turf: Hydroids (C); Tubularia (O); Alcyonium(O); Flustra(O). Cobble hydroid turf: Short turf of hydroids (C-A). Cobble Pomatoceros: Pomatoceros and barnacles (A). Bedrock/boulder silt sponge: Similar to boulder/cobble sponge above, but on bedrock/boulder. Boulder Laminaria: Small Laminaria hyperboraea (C); red algal turf (C). Bedrock sponge/Flustra: Bedrock with encrusting sponges (C-A) and Flustra (O-C). Bedrock Mytilus. Small Mytilus (A-SA); Asteria(C-SA); encrusting corralines (O). Bedrock and faunal turf: Hydroids (C); Tubularia(O); Alcyonium(O); encrusting and branching sponges(O-C). The maps were subsequently transposed into EUNIS in 2006 using expert judgement.

  • The section of the Menai Straits that were surveyed were divided into three parts. The hardness/roughness isopleths were combined using CAMRIS GIS to produce a composite map showing 7 types of group (very hard/very rough; hard/rough; moderately hard/moderately rough; moderately soft/moderately smooth; soft/moderately rough; soft/smooth; very soft/very smooth). A map for the whole of the survey area was followed by a map showing the biotope types as observed using the remote video, which are as follows (SA = superabundant; A = abundant; C = common; O = occasional) Sand/shell: Medium fine sand with shell: very silty. Coarse sand/silt: Coarse sand: very silty. Gravel: Barren Silty cobble: Silt accretion (A); Cerianthus (O-C); Urticina (O-C). Silty cobble/rich: Silt accretion (A); sponges (Haliclona, Halichondria) (C); hydroids (C); Urticina (O-C). Boulder/cobble sponge: Similar to above, but with sponges C-A. Cobble/bounder faunal turf: Hydroids (C); Tubularia (O); Alcyonium(O); Flustra(O). Cobble hydroid turf: Short turf of hydroids (C-A). Cobble Pomatoceros: Pomatoceros and barnacles (A). Bedrock/boulder silt sponge: Similar to boulder/cobble sponge above, but on bedrock/boulder. Boulder Laminaria: Small Laminaria hyperboraea (C); red algal turf (C). Bedrock sponge/Flustra: Bedrock with encrusting sponges (C-A) and Flustra (O-C). Bedrock Mytilus. Small Mytilus (A-SA); Asteria(C-SA); encrusting corralines (O). Bedrock and faunal turf: Hydroids (C); Tubularia(O); Alcyonium(O); encrusting and branching sponges(O-C). The maps were subsequently transposed into EUNIS in 2006 using expert judgement.

  • The HABMAP project was set up in response to the need for better spatial awareness of habitat distributions in the Southern Irish Sea. This work produced habitat maps of the seabed using novel predictive modelling techniques. This dataset is related to the predictive modelling only. The HABMAP Extension Project has built on the methods developed during the original project, and has repeated the modelling work using higher resolution / improved input datasets to help increase the accuracy of the predictive map outputs. The modelling work has also been extended to cover all of Welsh waters (previously cut-off at the Interreg funding boundary), notably including the Dee and Severn estuaries. The purpose of this data capture was to provide seabed habitat maps that could be used for conservation and management. Project outputs might be used in strategic planning, decision making for offshore developments, Marine Protected Area selection, sensitivity mapping and mapping essential fish habitats. However, because of the way the has been produced, and the fact that some data has been modelled and derived, the maps are not appropriate to act as the sole evidence for any specific planning or regulatory decision or assessment without further supporting studies or evidence. The project boundaries were as follows: Southern Irish Sea- land-based boundaries include the whole Welsh coast to the English border on the east side of the Dee Estuary in the north, and the whole Severn Estuary and Bristol Channel coastline in the south, extending as far as Morte Point (east of Ifracombe) in England. The southern project boundary then extends offshore (skirting the northern tip of Lundy) across to a point approx 60km west of Waterford on the Irish coast, including the whole SE Ireland coastline and offshore banks as well as parts of the Celtic Sea. The boundary then extends northwards along the Irish coast to a point approximately 40 km north of Dublin. The outputs of the project included a Combined Level3/Level4 habitat map, presented here after translation to the EUNIS habitat classification system from the Marine Habitat Classification System for Britain and Ireland. Each polygon of the original output contained up to 46 different biotopes, either predicted by the model or recorded as present, and presented in order of likelihood. Only the primary biotope has been taken from the original dataset to produce this EUNIS output, polygons originally containing more than one habitat are flagged in the "VAL_COMM" field. Information on whether the biotope was recorded as present or was a predictive output of the model, and a confidence value present in the original dataset have also been recorded in the "VAL_COMM" field